What is a paleontological species?

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.

This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.

This activity was selected for the On the Cutting Edge Exemplary Teaching Collection

Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories. The five categories included in the peer review process are

Context

Audience

Introductory paleobiology course.

Skills and concepts that students must have mastered

Experience with a compound microscope, knowledge of the morphological species concept, and taxonomic hierarchy. Experience with a graphical program and basic statistics is helpful, but can also be part of the learning experience.

How the activity is situated in the course

This is one of the first laboratory exercises, it follows a lecture-discussion of species concepts.

Goals

Content/concepts goals for this activity

A constructivist approach to developing an understanding of the species concept as it applies to fossil specimens.

Higher order thinking skills goals for this activity

Pattern recognition: using common morphological elements (e.g. molar cusps, cingula, crests) to differentiate among taxa. Evaluation of the significance of variation in molar metrics within and between species.

Description of the activity/assignment

In this two-part laboratory exercise, students explore the paleontological species concept by studying fossil rodent specimens and classifying them. This lab exercise follows a discussion of the species concept and is the first lab exercise in the course that gives students experience with fossil specimens. Part I: Students begin by studying casts of fossil mammal molars from which they construct clay models. This develops their ability to recognize the cusp pattern. Next, students are given 5 specimens that belong to a single species. First, they write qualitative descriptions of each specimen and then use an optical micrometer fitted to a microscope to collect data about molar length and width. Each group of students has a distinct species of the same rodent family, Ischyromyidae. Part II: The quantitative data is entered into a spreadsheet in Minitab, basic statistics are calculated and students plot molar length vs. width and/or molar area ln (LxW) vs. biostratigraphic level (if you want to include the time factor). (Class data is combined for the statistical analysis and graphing. An alternative approach, for a small class size, is to provide students with additional data points.) Each student pair must explain how they would classify each of the fossil specimens that they studied and the basis for their decision.

Determining whether students have met the goals

During a follow-up classroom discussion students explain what they have discovered about the morphological species concept. Students hand in their raw data, qualitative descriptions, and graphs in the form of a mini lab report. Finally, students answer questions in the next unit exam directly related to the concepts applied and/or skills developed in this exercise.

Download teaching materials and tips

Enough clay for students to work individually or in groups of three to make the molar model.

A model to follow (I use large casts of rodent molars) for the clay modeling part.

Fossils and/or casts

Hand lenses or microscopes

Access to a computer and Minitab or other graphical software, possibly graph paper.

Other taxa: I recommend using a taxonomic group that you are most comfortable with and one that you have ample fossils and/or casts for the exercise.

Basic statistics: The statistics can be as simple or involved as you choose. I include the mean, standard deviation, standard error, range and CV.

Common pitfalls: Be prepared for some students to work more quickly than others. Extensions of the exercise, such as creating more graphs or looking at more specimens to increase sample size will keep these students busy.

Suggested extensions:

Add time as another part of the data set.

Incorporate an investigation of intraspecific and interspecific variability.

Suggested opening to lab (one possibility):

Yesterday, we discussed several species concepts. We focused on the morphological species concept because it is often the one followed in taxonomic identification. While each of the species concepts have their merits, there are many challenges when it comes to a practical application of the definitions.

In today's lab, you will experience some of those challenges firsthand.

Learning Outcomes:

As a result of participating in this laboratory activity, you will be able to . . .

1. Describe the species concept as it applies to fossil specimens.

2. Use common morphological features (e.g. cusps and cingula) and metric elements (e.g. length and width of molars) to differentiate among taxa. (Interchange features to fit the type of fossil specimens you are using in the exercise.)

Provenance: Sean Fox, Carleton CollegeReuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

Provenance: GSAReuse: If you wish to use this item outside this site in ways that exceed fair use (see http://fairuse.stanford.edu/) you must seek permission from its creator.

GSA supports On the Cutting Edge

The mission of The Geological Society of America is to advance geoscience research and discovery, service to society, stewardship of Earth, and the geosciences profession. We support geoscience education at every level. Join us at http://www.geosociety.org/

Provenance: NAGTReuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

Value this site? Help us ensure its future.

The On the Cutting Edge website and workshop program are supported by the National Association of Geoscience Teachers (NAGT). Join today and your membership will help ensure that this site can continue to serve geoscience educators. Join NAGT today

Provenance: NAGTReuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.

Your NAGT membership helps make this site
possible. Thank you!

The On the Cutting Edge website and workshop program are supported by the National Association of Geoscience Teachers (NAGT). Your membership is helping to ensure that this site can continue to serve geoscience educators.

Images

Files

Provenance

Deborah Anderson, Saint Norbert College

Reuse

This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.